SK9637Y1 - Bioreactor for continuous production of biogas from liquid biosubstrate - Google Patents

Abstract

It is described a bioreactor for continuous biogas production consisting of a hermetically sealed vessel (28) which stands on a fixed above ground foundation construction (29), on top is covered by a conical cupola (27) and in side part is embedded a hopper (1) and a discharge hopper (7) with a neck and a drain a faecal outlet (14). At the bottom of the vessel (28), a squeegee (15) with a sludge pipe (17) and a faecal lever end (16) is mounted via a shaft (21) with an electric motor (18). Below the conical cupola (27) there is a gas discharge valve (3) with an overpressure safety valve (2).

Description

The field of technology

A bioreactor for the continuous production of biogas from a liquid biosubstrate is a device for using biodegradable waste as a renewable energy source. The technical solution concerns a device for the continuous production of biogas from a liquid biosubstrate in a reactor with control elements, sensors of the gas composition and the biological composition of the biosubstrate and, subsequently, a sophisticated adjustment of the composition of the biosubstrate by inoculation with suitable bacteria and additives of enzymes and nutrients, thus accelerating and intensifying the gasification process. The whole process is continuous, controlled by a computer with unique software that combines and doses the relevant ingredients. The technical solution belongs to the field of alternative energy sources.

Current state of the art

The production of biogas from biodegradable substances has been known for several millennia, there are known finds of biogas pit reactors in China from the historical period, where animal and human excrement were piped into a pit with a sealed lid, from which the biogas was piped to the burners.

Currently, home biogas stations (HomeBiogas) are starting to be implemented. It is a small biogas system designed for households. This system transforms organic waste of any origin into biogas, which can be used, for example, for cooking. The domestic biogas station also produces high-quality liquid fertilizer from the waste, which can be used to fertilize the garden. Every day, it can produce 5 to 8 liters of liquid organic fertilizer and biogas, which is enough for 2 to 4 hours of cooking.

Small agricultural biogas stations are also known as separate units, processing organic waste generated on the farm through anaerobic stabilization. It is mostly manure, poultry droppings or straw manure from livestock breeding. A smaller part is represented by organic household waste. From the point of view of the economy of the operation of the biogas station, it is expedient to process other suitable wastes as well. For example, the processing of kitchen waste, especially fatty waste, is proven by practice. In this case, a double effect will be achieved, biogas production will increase and financial compensation will be obtained for the disposal of waste from the producer, canteens, restaurants, etc.

Biogas produced during anaerobic fermentation is primarily used for the production of electricity and heat in a cogeneration unit. Any excess electricity is supplied to the public grid. The size of agricultural biogas plants depends on the size and focus of the farm. It is mostly in the range of 30 to 400 equivalent inhabitants in Europe.

In practice, a horizontal flow reactor (Darmstadt system) is used, the reactor is a steel or plastic, thermally insulated cylindrical tank with a diameter of usually 2 to 3 m, with a length according to the required capacity of the reactor. Considering the possibility of transport, such reactors are used with a volume of 50 to 100 m ³ . Used diesel tanks are often used. The tank is placed on concrete bases so that its slope is 3 to 5%. The manure is pumped into the higher part, the mixing of the contents of the reactor and the movement of the mixture towards the other, lower end is provided by paddles located on a shaft passing through the horizontal axis of the reactor. The mixing speed is slow, 1 to 3 revolutions per minute. This also corresponds to the low energy consumption for mixing, the 700- to 900-watt motor is sufficient for mixing 100 m ^{3 of} manure containing straw. The resulting biogas accumulates in the upper part of the reactor, from where it is removed to the gas reservoir. At the bottom, at the lowest point of the reactor, there are one or more blowdown valves. Heating is solved by the distribution of pipes inside the reactor. It is also common to place it in a double wall reactor or the heating is integrated with the stirring and is placed in the hollow shaft of the stirrer. Due to the relatively large investment costs, this type of reactor is mainly used for the fermentation of "dense wastes, such as poultry droppings, household waste or sludge with a higher content of straw, when the suitability of this type of solution is used."

Vertical reactors are based on standard, steel or concrete storage tanks for manure or grain. Converting such a tank to a reactor requires ensuring its gas tightness and thermal insulation. A high-quality concrete structure of the tank and roof, or supplemented with a hermetically sealed foil, is sufficient to ensure gas tightness. Common insulating materials such as polystyrene or glass wool are used for thermal insulation.

In some cases, the tanks are located below ground level. The tanks are produced in series, which is reflected in a lower price per unit of volume. The volumes used range from 250 to 600 m ³ , although there are reactors with volumes up to 1,200 m ³ . The depth of the reactors is usually 3 to 6 m and the diameter is 8 to 18 m. These reactors are often used as dual-purpose reactors, where they work with different dosing schedules during the year. In summer and autumn, they are filled only to a level ensuring a minimum retention time of 20 to 30 days. This prepares a reserve for the storage of several hundred m ³ of manure for the winter and spring periods, when it cannot or

SK 9637 Υ1 may not apply manure to the field. With a filled reactor, the retention time is over 60 days, which guarantees sufficient biogas production and stable operation of the fermenter even in winter. About 1/3 of the biogas plants in Germany use gas-tight tanks for the storage of stabilized manure and at the same time as biogas reservoirs. In some cases, a tank with a hermetically sealed membrane roof also serves as a fermenter. Double membranes are often used, when air under a pressure of 200 to 300 Pa is blown into the membrane space by a fan, which inflates the outer membrane serving as a roof, and the air pressure acting on the inner membrane, which separates the biogas, ensures sufficient overpressure of the biogas for further use (e.g. : Viessmann).

It follows from the published data that currently 111 biogas stations are connected in Slovakia with a total output of 103 MW and a planned annual production of 810,526 MWh of electricity. In the growing Slovak market for renewable energy sources, by 2013, investments in biogas stations were also more prominent. In 2014, however, there was a fundamental slowdown in their installation. The following overview shows the connected biogas power plants in the Slovak Republic according to information from the Office for the Regulation of Network Industries from July 2015, together with a description of the total installed power, the location of the biogas station and the technology.

The demonstration biogas plant in Slovakia is built in the University Agricultural Enterprise (VPP) of SPU in Kolínany near Nitra. It was put into operation already in 2000. It is designed to use excrement from 80 large cattle units (VDJ) for the production of biogas and subsequently for the cogeneration production of electricity (22 kWel) and thermal energy (45 kWt).

In the Czech Republic it is e.g. the Knežice biogas station currently has one anaerobic reactor (fermenter) with a volume of the sludge part of approximately 2,500 m ³ , above which there is a pressureless biogas gas tank with a volume of 800 m ³ , a covered homogenization collection tank with a volume of approximately 200 m ³ for mixing the incoming processed of raw materials and waste before they are pumped into the fermenter, a sanitation line for thermal sanitation of hazardous waste, a crushing line for grinding solid hazardous waste and two storage tanks for fermented sludge with a total volume of 2 x 6,300 m ³ . The sanitization line with the incoming crushing line and the cogeneration unit are located in the halls in the operating building of the biogas station. Other equipment and tanks belong to external objects. Currently known on the market are e.g. APD BIO GAS preparations, which is a mixture of bacterial cultures, enzymes and nutrients necessary for the activity of microorganisms supporting methanogenesis, an anaerobic process taking place through microorganisms. Due to their influence, the organic matter is more intensively degraded with the formation of methane, carbon dioxide or bicarbonate. The result of the action of preparations in biogas stations is a better, more efficient and faster decomposition of biomass (animal excrement, dendromass, biomass, liquid sludge from biological wastewater treatment plants, etc., but also waste from the processing and food industry). By dosing the preparation APD BIO GAS, more effective methanogenesis occurs and an increase in the amount of biogas produced, but their amount, time of use and, above all, the suitability of use for a specific composition of the substrate are not precisely determined.

As of October 2, 2020, according to the processed analysis, there are 113 biogas stations in Slovakia, of which 94 are for corn silage, while the rest are wastewater treatment plants (9) and waste landfills (10). Their average power is 1 MW, the total installed power is 115 MW, which gives technical space for a new solution of sophisticated bioreactors.

Some patented bioreactor solutions are also known.

DE10164458 A1 (FRAUNHOFER GES FORSCHUNG), July 10, 2003, describes a bioreactor for the cultivation of microorganisms with gas flow support, but which is not applicable for the production of biogas.

EP2379694 A1 (BAYER TECHNOLOGY SERVICES GMBH), October 26, 2011, relates to a bioreactor, the use of a bioreactor for the cultivation of microorganisms or cell cultures and also a method for cultivating microorganisms or cell cultures, not for the production of biogas in a continuous manner.

EP1685233 A1 (SAROKO ENERGY SYSTEMS LTD), 2 August 2006, describes a bioreactor which is designed for continuous or substantially continuous anaerobic digestion of organic matter. A bioreactor is a self-contained, small-scale unit that is suitable for small industrial or domestic use. The bioreactor contains a main reaction chamber and several reaction chambers. The chambers are arranged in such a way that organic substances can pass by gravity from the inlet through the chambers and into the main reaction chamber. Additional organic matter can be introduced into the bioreactor by entering the first counter chamber without significantly affecting the oxygen level in the main reaction chamber, thereby maintaining the efficiency of the methane production rate during digestion in the main chamber. The bioreactor can be connected to the domestic sewage drain. The mentioned solution does not include the possibility of adding additives to the process, ultrasonic extraction equipment or multifunctional biogas and biosubstrate sensors.

US2018214831 A1 (LIFE TECHNOLOGIES CORP), Aug. 2, 2018, describes the construction of a bioreactor that includes a support vessel with an active interior surface, the support housing having a side wall with an opening through which a communication line passes. The design also includes mixing elements on the shafts

SK 9637 Υ1 and more specifically bioreactor systems with carriers for test tubes and probes. It contains several figures and it is understood that these drawings show only typical embodiments of the technical solution and therefore cannot be considered as limiting its scope. The technical solution is not intended for biogas production.

SK287581 B6 (GFE PATENT AS), March 4, 2011, in the method organic material is processed by pressure cooking with lime, it schematically and verbally describes the device for carrying out this method with the addition that it also produces biogas. The mentioned solution does not represent a design innovation, the claims address biochemical processes in detail.

The essence of the technical solution

The essence of the technical solution is a sealed vessel with a volume of 50 to 100 m ³ made of heat-insulating material reinforced with spiral heating/cooling pipes on a fixed above-ground structure. The top of the bioreactor is covered by a conical dome with a transparent mounting flange. A recessed funnel with a neck and outlet below the level of the biosubstrate, controlled by a level meter, is used to continuously fill it with liquid biosubstrate. Under the dome of the reactor (above the surface of the float) there is a space - a gas tank. Below the surface are at least two propeller electric stirrers, a scraper at the bottom of the reactor, and the biosubstrate is extracted ultrasonically with an extraction rod into simpler organic molecules. The temperature regime is determined by the control system in the range of 30 to 75 °C. Inputs to the control system, information on the composition of biogas and biosubstrate are imported from multifunctional sensors - temperature, pH, chemical elements, organic substances and microbiological processes as an input for the software for dosing ingredients through additive funnels, fitted with a lid with a filling hole and a dosing valve with an electric motor .

The float from the water surface is removed through a funnel for further processing. Sludge at the bottom of the reactor is driven by a rotary scraper driven by an electric motor through a shaft into the sludge pipe for further processing and use. The biogas is removed by overpressure into the utility pipe through the biogas detector and the overpressure is secured by a safety valve.

The technical components of the bioreactor are the mounting flange, wiring distribution box, inlets, outlets and piping of the cooling/heating medium with standard terminals, as well as a ladder and a door.

The advantage of the bioreactor is primarily the continuous, hermetically sealed filling and discharge of the biosubstrate after fermentation, no degassing occurs. The advantage is the high yield of biogas, but also the possibility of connection to further technical equipment, such as the village's heating system, cogeneration unit, as well as the processing of dewatered float and sludge by bagging and the subsequent shipment of fertilizer.

Overview of images on drawings

In fig. 1 shows a cross-section of a bioreactor for the production of biogas from a liquid biosubstrate.

In fig. 2 shows a top view of a bioreactor for the production of biogas from a liquid biosubstrate.

In fig. 3 shows a view in direction A of a bioreactor for the production of biogas from a liquid biosubstrate.

In fig. 4 shows a view in direction B of a bioreactor for the production of biogas from a liquid biosubstrate.

In fig. 5 shows a C-direction view of a bioreactor for the production of biogas from a liquid biosubstrate.

Implementation examples

A bioreactor for the continuous production of biogas from a liquid biosubstrate consists of a hermetic container 28 with a volume of 50 to 100 m ³ made of heat-insulating material, a reinforced spiral heating/cooling pipe 11, with inlets 9 and outlets 12 for connecting the cooling/heating medium, a brine that stands on a solid above-ground foundation structure 29. The top of the bioreactor is covered by a conical dome 27 with a transparent mounting flange 4. It is filled with liquid biosubstrate by a sunken hopper 1 with a mouth and outlet below the level of the biosubstrate, controlled by a level gauge 6. Under the reactor dome (above the float level) is space - gas reservoir, fitted with a 30 biogas detector. The biogas is discharged by excess pressure into the utility pipe through the discharge gas valve 3 and the excess pressure is ensured by the safety valve 2. The propeller electric stirrers 13 are fixed tangentially on the inner shell of the container, where the ultrasonic extraction rod 20 is also fixed in an oblique, centripetal direction.

SK 9637 Υ1

The innovative design element of the bioreactor is hermetically fitted funnels 10 ingredients, at least three in number, with lids 26, a closing dosing flap 25 with an electric motor, which, based on information from the biogas detector 30, multifunctional sensor 8, dose the ingredients into the fermentation process.

After fermentation, the floatate from the surface of the biosubstrate is removed from the top through a discharge funnel 7, with a fitted fecal terminal 14, suitable for removal by fecal vehicles for further use. The second output from the bioreactor is sludge, which is driven by the squeegee 15 into the dewatering pipe 17, terminated by the faecal lever terminal 16, for discharge and directly into the prepared containers. The movement of the squeegee 15 is provided by a mechanism with a shaft 21 and an electric motor 18. The structural elements of the bioreactor also include a ladder 22 located on the side of the container 28, a door 23 at the entrance to the space under the container, and in that space an electrical control box 19 for placing circuit breakers of electrical distribution, and also distribution box 5 of the control system 24.

Industrial applicability

A bioreactor for the continuous production of biogas from a liquid substrate can be advantageously used where there is no wastewater treatment plant and where it is necessary to export domestic and corporate municipal wastewater from cesspools over long distances for disposal, but primarily liquid waste from catering establishments, the food and processing industry , but also waste oils. The decomposition process of bio-waste in such a composition is in different stages, therefore it is necessary to homogenize it by mixing and ultrasound, analyze and adjust the fermentation process so that biogas is extracted in an optimal amount. For this purpose, multifunctional sensors of temperature, pH, chemical elements, organic substances and microbiological processes and in the fermentation process, such as fatty acids (formic, acetic, propionic, lactic, valeric, etc.), load of FOS/TAC fermenters, biogenic elements (phosphorus , nitrogen, potassium, calcium, sodium, magnesium, etc.) in settings according to the composition of the biosubstrate. This composition and conditions are served by the software for dosing the ingredients, which are mainly methanophilic bacteria in a wide spectrum (order Methanobacteriales, order Methanococcales, order Methanomicrobiales, etc.) and nutrients in acidic and alkaline environments.

The produced biogas is also used to heat the biosubstrate to the temperature determined by the control system in the optimal range. The discharged float and sludge after dewatering serves as a high-quality fertilizer, and the water is returned to the reactor as a high-quality inoculation ingredient.

By processing biomass in a bioreactor, a large amount of waste from small sources, which would otherwise be a burden on the environment, can be efficiently utilized. In addition, the production of biogas in a bioreactor does not produce its own waste, because all outputs are environmentally acceptable for further use.

Claims (6)

CLAIMS FOR PROTECTION 1. A bioreactor for the continuous production of biogas from a liquid biosubstrate, characterized by the fact that it consists of a sealed container (28) with a volume of 50 to 100 m ³ made of heat-insulating material, which stands on a fixed above-ground foundation structure (29) and is covered by a conical dome on top (27) and a sealing funnel (1) and a discharge funnel (7) with a neck and outlet with fecal end (14) are embedded in it on the side, and a squeegee (15) is mounted on its bottom via a shaft (21) with an electric motor (18) ) with a sewage pipe (17) at the end with a faecal lever end (16), while a gas discharge valve (3) with an overpressure safety valve (2) is located under the conical dome (27). 2. A bioreactor for the continuous production of biogas from a liquid biosubstrate according to claim 1, characterized by the fact that spiral heating/cooling pipes (11) with inlets (9) and outlets (12) for connection are laid around the perimeter of the hermetic container (28) cooling/heating medium. 3. A bioreactor for the continuous production of biogas from a liquid biosubstrate according to claims 1 and 2, characterized by the fact that propeller electric stirrers (13) are placed in the tangential direction, a level gauge (6) is placed on the surface of the biosubstrate, and an ultrasonic extraction rod (20) is used for biochemical treatment of the substrate ) immersed in the biosubstrate. 4. A bioreactor for the continuous production of biogas from a liquid biosubstrate according to claims 1 to 3, characterized by the fact that at least three funnels (10) of ingredients with lids (26), a closing dosing valve (25) are hermetically mounted on the side of the hermetically sealed container (28). with an electric motor for dosing ingredients into the fermentation process based on information from the biogas detector (30) located under the dome (27) and from the multifunctional sensor (8) immersed in the biosubstrate. 5. A bioreactor for the continuous production of biogas from a liquid biosubstrate according to claims 1 to 4, characterized in that it includes an externally located control system (24) for dosing ingredients. 6. A bioreactor for the continuous production of biogas from a liquid biosubstrate according to claims 1 to 5, characterized in that its technical equipment includes a ladder (22) which is located outside the container (28), a mounting flange (4) covering the top of the dome (27) ), the door (23) locking the entrance to the space of the base structure (29), where the distribution box (5) and the electrical control box (19) are stored.